Calcium and Improved Bone Mineral Density

Across 3 studies, 1 reported a small beneficial effect of calcium supplementation on bone mineral density, while 2 found neutral effects. The beneficial finding is from a meta-analysis in postmenopausal women with osteoporosis; the neutral studies involved kidney transplant recipients and postmenopausal women with type 2 diabetes. The median study duration was 504 days (from 1 study). Overall evidence is mixed and preliminary.

• Studied populations: postmenopausal women with osteoporosis

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. The beneficial effect was observed only in postmenopausal women with osteoporosis; neutral findings in other populations (kidney transplant recipients, women with type 2 diabetes) suggest the benefit may not generalize. One study reported a significant negative effect (MD = -5.85) that was classified as neutral, indicating possible adverse direction in certain groups.